The present invention relates to a refractory plate assembly employed in a sliding closure unit for controlling the discharge of molten metal from a metallurgical vessel. More particularly, the present invention relates to such an assembly wherein the sliding closure unit is of the type including a casing to be fixed to the metallurgical vessel adjacent an outlet thereof, a stationary refractory plate mounted in the casing and having a discharge opening aligned with the vessel outlet, a movable refractory plate having therethrough a discharge opening, and a movable frame supporting the movable refractory plate in planar abutting contact with the stationary refractory plate and movable between an open position with the discharge openings of the movable and stationary refractory plates in alignment and a closed position with the discharge openings out of alignment. Further specifically, the present invention relates to such an assembly wherein the movable refractory plate is provided with a closing face and a movable plate or control member guided therein on the frame for modifying the size of the discharge opening in the movable refractory plate and thereby regulating the discharged stream of molten metal.
Such an assembly is disclosed in German DE-OS No. 28 34 643 wherein beneath the refractory bottom or stationary plate is mounted a lower plate in the form of two partial plates sliding linearly in a manner symmetrical to the teeming or discharge axis and supported in a sliding frame. Throughout the length of the range of sliding movement between the plate faces directed toward each other and controlling the pouring or discharged molten stream, the plates are flanked by lateral guides to shield the pouring stream during its discharge to the outside. Solely for sealing the plate opening, one of the partial plates has a closing face or is provided with a separate closing plate. The lateral guides may be mounted on a plate coupled with a drive mechanism, and such plate is U-shaped and receives between sides thereof the other plate. A drive connection between the two plates enable their symmetrical adjustment toward and away from each other by means of the drive mechanism acting on one plate. This known construction presents a number of problems with respect to sealing the controlling plate face area. Further, this known construction is relatively expensive, particularly because it employs two plates in symmetrical cooperation with each other by means of a connecting drive, even though the advantages of a coaxial control and slit-shaped concentration of the pouring stream are important. Another disadvantage is that it is more difficult to replace the refractory parts of the plate assembly controlling the pouring stream, compared to traditional standard movable refractory plates with at least one teeming hole and a closing surface or face. Also, this known assembly cannot be used on rotary movable or swivelly movable sliding closure units.